Most deaths in high rise building fires occur on upper stories beyond the reach of conventional fire truck ladders. In attempting to minimize such deaths, various portable type reel and line devices have been proposed which can be used by an individual in a high rise building to lower himself to the ground by paying out the line or cable from the reel.
Notwithstanding that many types of portable safety line reel type fire escape devices have been proposed, there has not, to the best of our knowledge, really been any widely accepted use of the same.
Part of the problem is that the devices themselves as have been proposed in the past are relatively expensive and are not always foolproof in operation. For example, many such devices rely on a mechanical device to provide a retarding force or frictional drag on the reel in order to slow the rate of descent of a person to a safe value. It is difficult to adjust such mechanical devices to provide a proper degree of friction. If there is too little friction, a person will drop too quickly and can be seriously injured when striking the ground. If there is too much friction, the person cannot descend rapidly enough to escape the fire.
In U.S. Pat. No. 4,088,201 there is disclosed a greatly improved fire escape safety line and reel or spool arrangement utilizing a viscous fluid as a retardant or frictional drag on the spool. More particularly, the spool on which a line or cable is wound is enclosed within a casing. The casing itself includes a side housing or extended portion in an axial direction and serves to house a rotatable member on the same shaft as that supporting the spool. As the cable unwinds, this rotatable member will rotate within the auxiliary housing. An appropriate viscous fluid is provided in the housing to result in a frictional drag on the member and thus the spool thereby controlling the rate of descent of a person.
The device itself is in the form of a casing arranged to be secured to a projection or hook or other member embedded in a high rise building. The free end of the cable from the casing in turn connects to an appropriate safety belt or harness supporting the person who is attempting to escape. The cable itself is payed out from a peripheral opening on the casing. After the person is lowered to the ground, he or she simply disconnects the free end of the cable.
While this device as covered in the patent represents a great advance in the art in that a very controlled descent is realized, there are still some problems. First, the device can only be used once since the casing intself is secured to the building and ultimately would be destroyed by a fire. Second, the provision of the auxiliary housing on the casing makes the device somewhat more bulky than would be desirable in the design of a portable escape device. Finally, the tangential opening through which the free end of the cable passes from the casing is such that if a load on the cable is suddenly relieved, part of the cable may "jump" back into the casing and possibly cause a jamming of the spool. In this respect, it will be appreciated that the cable is under tension when supporting a human body and if the weight of the body is suddenly relieved as might occur if the person descending encountered a ledge, the elasticity of the cable could result in the same "jumping" back into the casing resulting in the aforesaid entanglement.
The above-noted U.S. patent and the various references cited therein constitute the closest prior art of which we are aware to the present invention.